This is the first renewal of Chemistry-Biology Interface (CBI) training grant T32 GM08804. We have designed an interdisciplinary program for training students (and faculty) at the interface of biological, medicinal, and traditional chemistry, called the Biological Chemistry Program (BCP). This program, which began in the fall of 2000, provides a focused, cross-disciplinary education for students interested in biological chemistry. The program is fully integrated into the three participating departments and students may obtain a degree in Chemistry, Biochemistry and Molecular Biophysics, or Pharmacology and Toxicology (Medicinal Chemistry Division) while following the Biological Chemistry Training Program. Students undertake coursework in all three departments, perform research rotations in at least two departments and participate in the weekly BCP research forum, where students and faculty present research results. Importantly, students may work with anyone in the program, regardless of departmental affiliation, allowing for true multi- disciplinary research efforts. The training faculty includes 34 highly-active research groups from four departments. Students remain active in the BCP until graduation. There are 36 students currently following the training program, 21 of which are training grant eligible; an additional 6-10 students are expected to join in the fall. Since inception in 2000, 8 students have completed the program with a PH.D. degree. Training grant slots are generally made for years 2 and 3 in the program, allowing training grant recipients great flexibility in assembling a multi-disciplinary research project. Fellowships are awarded near the end of the student's second semester, before they choose a thesis advisor, to assist in assembling a broad-based team. For years 6-10, we request 8 training grant slots per year, allowing for four 2-year fellowships to be awarded per year, and ~1/3 of our training-grant-eligible students to be funded at any given time. Training at the Chemistry-Biology Interface is highly relevant for advances in public health. Many of the most important discoveries occur at the intersection of one or more disciplines, where the knowledge of one field is brought to bear on the problems of another. By blending Chemistry, Medicinal Chemistry and Biochemistry, our trainees are poised to make the next breakthroughs in drug discovery, disease detection, disease prevention, and the discovery of the underlying causes of disease.